The present invention relates to an envelope supply device and, more particularly, to an envelope feeder in an envelope insertion machine.
In a typical envelope insertion machine for mass mailing, there is a gathering section where the enclosure material is gathered before it is inserted into an envelope. This gathering section includes a gathering transport with pusher fingers rigidly attached to a conveying means and a plurality of enclosure feeders mounted above the transport. If the enclosure material contains many documents, these documents must be separately fed by an envelope supply device from different enclosure feeders. After all the released documents are gathered, they are put into a stack to be inserted into an envelope in an inserting station. Envelopes are separately fed to the inserting station, one at a time, and each envelope is placed on a platform with its flap flipped back all the way. At the same time, a vacuum suction device or mechanical fingers are used to keep the envelope on the platform while the throat of the envelope is pulled away to open the envelope.
Before envelopes are fed to the insertion station, they are usually supplied in a stack in a supply tray. Envelopes are then separated by an envelope feeder so that only one envelope is fed to the insertion station at a time. For that reason, an envelope feeder is also referred to as an envelope singulator. In a high-speed insertion machine, the feeder should be able to feed single envelopes at a rate of approximately 18,000#10 envelopes per hour. At this feeding rate, it is critical that only a single envelope at a time is picked up and delivered to the insertion station.
In the past, as in the envelope feeder disclosed in U.S. Pat. No. 5,415, 068 (Marzullo), envelopes are singulated by using a belt to transport the last envelope in a stack to move downstream. If one or more envelopes move along with the last envelope, it will be stopped by a mechanical retarder which provides a friction force against the moving envelope. In the envelope feeder disclosed in Marzullo, the envelopes are stacked vertically and the bottom of the stack is spring-loaded to allow envelopes to be separated from the top of the stack. This type of envelope feeder requires adjustments to be made to the feeder or the transport and flapping section of the envelope processor system when envelopes of a different size is singulated. Furthermore, although the top separation design can eliminate some of the problems traditionally associated with pack pressure on units that rely on gravity to deliver the envelopes toward the separating device, envelope restocking is quite inconvenient.
The present invention provides a method and apparatus for feeding envelopes in an envelope insertion machine.
According the first aspect of the present invention, the method for feeding envelopes from a stack of envelopes in an envelope supply device includes the steps of: positioning a rotatable pneumatic apparatus at a pickup point at the proximity of the downstream end of the envelope stack; creating a negative air pressure on the pneumatic apparatus so as to attach an outer-most envelope of the envelope stack at the downstream end to the pneumatic apparatus; rotating the pneumatic apparatus in order to move the attached envelope away from the pickup point; and releasing the attached envelope from the pneumatic apparatus.
Additionally, the method comprises the step of turning off the negative air pressure on the pneumatic apparatus so as to release the attached envelope from the pneumatic apparatus. However, it is preferable to use a strip-away plate to strip off the attached envelope from the pneumatic apparatus.
Preferably, the pneumatic apparatus includes an outer cylinder having one or more openings for air passage, and an inner cylinder having one or more apertures for air passage located between the outer cylinder and the negative air pressure creating mechanism. The inner cylinder can be rotated to a first position relative to the outer cylinder to allow the negative air pressure creating mechanism to be operatively connected to the openings in order to create the negative air pressure on the pneumatic apparatus. The inner cylinder can also be rotated to a second position relative to the outer cylinder for operatively disconnecting the negative air pressure creating mechanism from the openings in order to turn off the negative air pressure on the pneumatic apparatus.
The second aspect of the present invention is a pneumatic apparatus to be used in an envelope supply device to pick up one envelope at a time from a stack of envelopes at a pickup point, wherein the pneumatic apparatus is used in conjunction with a vacuum pump or any negative air pressure producing mechanism. The pneumatic apparatus includes: a rotatable feeding head having one or more openings for air passage; a rotating mechanism to rotate the feeding head in order to position the openings at the pickup point; a device for operatively connecting the openings to the vacuum pump for creating a negative air pressure at the openings in order to pick up and attach to the feeding head the outer-most envelope of the envelope stack at the downstream end; and a moving mechanism to move the attached envelope away from the pickup point in order to release the attached envelope from the feeding head. Preferably, the pneumatic apparatus also includes a device to turn off the negative air pressure at the openings when the feeding head is in the process of picking up an envelope.
The third aspect of the present invention is an envelope supply device for picking up envelopes from a stack of envelopes at a pickup point, wherein the envelope supply device is used in conjunction with a vacuum pump. The envelope supply device includes: a rotatable pneumatic feeding head operatively connected to the vacuum pump; a rotating mechanism to rotate the pneumatic feeding head to the pickup point in order to attach an outer-most envelope of the envelope stack to the pneumatic feeding head; and a movement device to move the attached envelope away from the pickup point in order to release the attached envelope from the feeding head. Preferably, the envelope stack is placed on a main deck having a lead edge deck which is substantially perpendicular to the surface of the main deck. The lead edge deck is used to justify the lead edge of the envelopes in the envelope stack. Preferably, the main deck is tilted in an angle so that the gravity will help pull the lead edge of envelopes toward the lead edge deck. The envelope supply device further includes a pusher back paddle placed behind the envelope stack to constantly push the stack toward the downstream end of the envelope supply device.
The present invention will become apparent upon reading the descriptions taken in conjunction with FIGS. 1-4E.
FIG. 1 is an isometric view showing the envelope supply device according to the present invention.
FIG. 2 is an isometric view showing the pneumatic feeding head.
FIG. 3 illustrates a cross sectional view of the pneumatic feeding head.
FIG. 4A through FIG. 4E illustrate the principle of the envelope supply device.